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<br />DRAINAGE CRITERIA MANUAL <br /> <br />RUNOFF <br /> <br />II = Inflow into the reach at the beginning of the time <br />increment. <br /> <br />. <br /> <br />C = A coefficient found using Equation 4-8 <br /> <br />C = 1 - (l-c )bt/B <br />1 <br /> <br />(4-8) <br /> <br />In which, C1 = V/(V + 1.7) <br /> <br />K = L/(3600V) <br /> <br />B - KC <br />- 1 <br /> <br />L = Channel reach length in feet. <br /> <br />v = Translation velocity in feet per second <br /> <br />~t = Unit time increment in hours; has to be less than or <br />equal to one-fifth of TR. <br /> <br />. <br /> <br />TR = Time of rise of the storm hydrograph defined as the <br />time from beginning of flow to peak flow. <br /> <br />It is easiest to illustrate the use of the Convex Method through an example in <br />4.13.4 <br /> <br />4.13.4 Example - Convex Routing Method <br />Given: Same watershed and storm hydrographs given in 4.13.2. <br /> <br />Required: Composite storm hydrographs at design points Band C calculated <br />using the Convex Routing Method. <br /> <br />Solution: <br /> <br />Step 1. Determine flow to be used to calculate translation velocity V <br />for reach A-B. Enter on Table 4-6 the values for Q and 3/4 Q : <br />p p <br /> <br />. <br /> <br />5-1-84 <br />